cmd/golangorg, _content: add <head> tag before </head>

The HTML spec is permissive enough that missed <head> tags do not
generally cause problems, but fix up a few places for consistency.

The xTemplate one got dropped in CL 480840 while adding a <title>
element.

Change-Id: I56bf0c5c63ae02df9469eb2de68d3461014ab541
Reviewed-on: https://go-review.googlesource.com/c/website/+/790820
Reviewed-by: Sean Liao <sean@liao.dev>
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
LUCI-TryBot-Result: golang-scoped@luci-project-accounts.iam.gserviceaccount.com <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
diff --git a/_content/blog/context/server/server.go b/_content/blog/context/server/server.go
index 68bf37a..ba004ed 100644
--- a/_content/blog/context/server/server.go
+++ b/_content/blog/context/server/server.go
@@ -88,7 +88,7 @@
 
 var resultsTemplate = template.Must(template.New("results").Parse(`
 <html>
-<head/>
+<head></head>
 <body>
   <ol>
   {{range .Results}}
diff --git a/_content/talks/2015/go-for-java-programmers/frontend.go b/_content/talks/2015/go-for-java-programmers/frontend.go
index 1653445..dfe6c7f 100644
--- a/_content/talks/2015/go-for-java-programmers/frontend.go
+++ b/_content/talks/2015/go-for-java-programmers/frontend.go
@@ -70,7 +70,7 @@
 
 var resultsTemplate = template.Must(template.New("results").Parse(`
 <html>
-<head/>
+<head></head>
 <body>
   <ol>
   {{range .Results}}
diff --git a/_content/talks/2016/applicative/frontend.go b/_content/talks/2016/applicative/frontend.go
index 45f9f96..50db3dd 100644
--- a/_content/talks/2016/applicative/frontend.go
+++ b/_content/talks/2016/applicative/frontend.go
@@ -81,7 +81,7 @@
 
 var responseTemplate = template.Must(template.New("results").Parse(`
 <html>
-<head/>
+<head></head>
 <body>
   <ol>
   {{range .Results}}
diff --git a/cmd/golangorg/server.go b/cmd/golangorg/server.go
index 3b015f9..8727c49 100644
--- a/cmd/golangorg/server.go
+++ b/cmd/golangorg/server.go
@@ -690,6 +690,7 @@
 
 var xTemplate = template.Must(template.New("x").Parse(`<!DOCTYPE html>
 <html lang="en">
+<head>
 <title>The Go Programming Language</title>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
 <meta name="go-import" content="golang.org/x/{{.Proj}} git https://go.googlesource.com/{{.Proj}}">